Health technology Ligase chain reaction (LCR) testing in women with genital infections with Chlamydia trachomatis (CT).

Transcription

1 Screening op asymptomatische infectie met Chlamydia trachomatis in de zwangerschap: gunstige kosteneffectiviteit bij een prevalentie van tenminste 3% [Screening for asymptomatic Chlamydia trachomatis infection in pregnancy: cost-effectiveness favorable at a minimum prevalence rate of 3% or more] Postma M J, Bakker A, Welte R, van Bergen J E, van den Hoek J A, de Jong-van den Berg L T, Jager J C Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology Ligase chain reaction (LCR) testing in women with genital infections with Chlamydia trachomatis (CT). Type of intervention Screening. Economic study type Cost-effectiveness analysis. Study population The study population was a hypothetical group of 10,000 pregnant women and their partners. No further details for this population were provided. Setting The community (screening in general practice). Dates to which data relate Effectiveness data was derived from literature published between 1993 and Population statistics were 1999 data from the Dutch Central Bureau of Statistics (CBS). Prices were derived from publications from 1993 and The price year was not specified. Source of effectiveness data Effectiveness data were derived from several publications. No formal review of the literature was described. For a full description of the pharmacoeconomic model used, the authors refer to a previous publication (See 'Other publications of related interest' - 1). Modelling A disease and intervention model (in effect a decision tree) was used. This described the progression of disease and the effects of screening. This model is described in a previous publication (See 'Other publications of related interest' - 1). Outcomes assessed in the review Data on health care needs for CT complications were derived from various sources. The outcomes assessed in the review were the percentage of women who stop therapy due to complications, and the effectiveness of therapy among Page: 1 / 6

2 those who finish therapy. Data about the development of complications, in particular the percentage of women with pelvic inflammatory disease (PID), chronic pelvic pain, infertility or ectopic pregnancy due to CT, and new-born babies with pneumonia or with conjunctivitis, were derived from various sources. The process was described elsewhere (See 'Other publications of related interest' - 1). Study designs and other criteria for inclusion in the review No details were provided. Sources searched to identify primary studies Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data Number of primary studies included In the original study (See 'Other publications of related interest' - 1) ten primary studies were included. In this study four additional studies were included. Methods of combining primary studies Investigation of differences between primary studies Results of the review The authors report two possible treatments for CT: erythromycin and amoxicillin. Complications of erythromycin lead, in 15.6% of cases, to termination of treatment. In all other cases, the percentage cured is 94.9%. For amoxicillin the effectiveness is 92.6%. Termination of treatment was not taken into account as it occurred infrequently. The resulting effectiveness of the erythromycin followed by amoxicillin in case of serious complications regime is approximately 95%. Information on the development of complications were described in a previous publication (See 'Other publications of related interest' - 1). Methods used to derive estimates of effectiveness The sensitivity and specificity of the ligase chain reaction test (LCR-test) were based on an assumption made by the Page: 2 / 6

3 authors. Re-infection of treated women and infection by partners was taken into account in the model. Estimates of effectiveness and key assumptions The sensitivity of the LCR test was assumed to be 80% and the specificity 99.9%. These data also formed part of the input parameters for the model. In the model all partners were treated with azithromycin. The transmission percentage, based on one partner per pregnant woman, was estimated at 68%. The effectiveness of azithromycin was estimated to be 95%. Treatment of the partner may lead to the avoidance of a rare long-term complication of CT: epididymitis. In the case of symptomatic re-infections (estimated at 40% of re-infections in women and 50% of re-infections in men) repeated treatment was assumed for both partners. Measure of benefits used in the economic analysis The measures of benefit was the number of serious complications avoided: pelvic inflammatory disease (PID), chronic pelvic pain, ectopic pregnancy, infertility and pneumonia in new-borns. Health states were not given values. Direct costs Direct costs were based on estimates, which were described in a previous publication (See 'Other publications of related interest' - 1) and no further details of breakdown or resource quantities were given. Estimates of the costs of treatment medication (tariffs from the Centraal Orgaan Tarieven Gezondheidszorg) and GP visits were taken from the literature. The price year used was not specified. Costs were discounted at 4% per year. Statistical analysis of costs No statistical analysis was reported. Indirect Costs The indirect costs of production loss were described in a previous publication (See 'Other publications of related interest' - 1) as was the price year. Costs were discounted at 4% per year. Currency Dutch guilders (Dfl). Sensitivity analysis The following one-way sensitivity analyses were performed: including the direct costs only; varying the discount rate between 0% and 7%; assuming a sensitivity of the LCR-test of 90% instead of 80%; discounting serious complications avoided; CT screening offered for the first pregnancy only. Page: 3 / 6

4 Estimated benefits used in the economic analysis Estimated benefits were reported as part of the sensitivity analysis. The reader is referred to the synthesis of costs and benefits results below. Cost results The costs of erythromycin and amoxicillin were approximately Dfl each. The mean direct costs of the erythromycin followed by amoxicillin in case of serious complications regime was approximately Dfl (including apothecary and GP costs). Indirect costs were estimated at a production loss of one day, due to serious complications of erythromycin, leading to treatment termination. Direct and indirect costs associated with complications were the same as in the previous publication (See 'Other publications of related interest' - 1), with the exception of the direct medical costs for the treatment of pneumonia in new-borns, which were now estimated at Dfl 15,200.00, based on improved cost estimates. The costs of long-term complications of CT infection during pregnancy were estimated at Dfl 1, This was based on pelvic inflammatory disease and chronic pelvic pain of 62%; ectopic pregnancy and infertility 17%; Pneumonia and conjunctivitis in new-borns 20%; and epididymitis 1%. The LCR-test cost Dfl per test. Synthesis of costs and benefits Net costs were expressed as the difference between the costs of screening with treatment of CT-positives and the benefits of avoided costs from treating complications. Net costs were reported as part of the sensitivity analysis (see the synthesis of costs and benefits below). Results were presented for a group of 10,000 pregnant women with a CT-prevalence of 1-4%. Results were expressed as the number of avoided serious complications (ASC), net costs and cost-effectiveness (net costs per avoided serious complication). CT prevalence 1%: Costs, Dfl 363,200; avoided costs, Dfl 100,400; Number of ASC, 37; Net cost per ASC, Dfl 7,110. CT prevalence 2%: Costs, Dfl 376,000; avoided costs, Dfl 200,900; Number of ASC, 74; Net cost per ASC, Dfl 2,370. CT prevalence 3%: Costs, Dfl 388,900; avoided costs, Dfl 301,300, Number of ASC, 111; Net cost per ASC, Dfl 790. CT prevalence 4%: Costs, Dfl 401,700; avoided costs, Dfl 401,800; Number of ASC, 148; Net cost per ASC, costsaving. The minimal prevalence of CT-infection during pregnancy for which CT-screening is cost-saving was calculated for the following scenarios: Basic analysis: 4.00; Sensitivity analysis, including only direct costs: 5.18; Sensitivity analysis, assuming 90% sensitivity for LCR-test: 3.56; Sensitivity analysis, using 0% discount rate: 3.89; Sensitivity analysis, using 7% discount rate: 4.08; Sensitivity analysis, discounting avoided serious complication: 4.01; Page: 4 / 6

5 Sensitivity analysis, offering screening only for first pregnancy: 3.82; The minimal prevalence of CT-infection during pregnancy for which CT-screening is costs less than Dfl 1,000 per avoided serious complication (ASC) was calculated for the following scenarios: Basic analysis: 2.82; Sensitivity analysis, including only direct costs: 3.35; Sensitivity analysis, assuming 90% sensitivity for LCR-test: 2.51; Sensitivity analysis, using 0% discount rate: 2.76; Sensitivity analysis, using 7% discount rate: 2.85; Sensitivity analysis, discounting avoided serious complication: 2.83; Sensitivity analysis, offering screening only for first pregnancy: 2.70; Authors' conclusions The authors reported that no recent Dutch data on CT prevalence in pregnancy had been published. Therefore, given the current information, antenatal CT screening can be recommended from a pharmacoeconomic perspective if CT prevalence in pregnancy is 3% or more. CRD COMMENTARY - Selection of comparators Although no explicit justification for the choice was given, the comparator of no screening was appropriate and allowed the relative costs and benefits of the intervention to be assessed. You, as the user of the database, need to consider if this is appropriate to your setting. Validity of estimate of measure of effectiveness It is difficult to assess objectively the validity of the estimates of effectiveness as some were derived from a review of the literature, for which details of the search strategy and inclusion criteria were not provided. Other estimates were based on the authors' assumptions for the sensitivity and specificity of the LCR test. However, the authors did mitigate this to some degree by the sensitivity analyses that were undertaken to address variability in their estimates. Validity of estimate of measure of benefit The benefit measure was appropriate and was derived directly from the effectiveness estimates using modelling. Ideally, in order to make comparison with other technologies, one would want a valuation of the number of complications avoided in terms of quality of life and/or preferences. Validity of estimate of costs It was difficult to assess the validity of various estimates as most information was published in a previous paper (See 'Other publications of related interest' - 1), and was not reported in this paper. Based on information from the previous publication we can state that the authors adopted thorough and progressive techniques in their cost analysis. For example in the adoption of discounting for relevant complications, the use of friction costs to assess productivity losses, the inclusion of price years and adjustments for inflation, and the listing of costs for all relevant complications and tests. The adoption of the societal perspective also helped with the validity of the cost results and therefore the generalisability to other settings. Appropriate sensitivity analyses were also undertaken to account for variability in the estimates used in the modelling. Page: 5 / 6

6 Powered by TCPDF ( Other issues Although no recent Dutch data on CT prevalence in pregnancy were published, the authors noted that the minimum prevalence of CT-infection at which screening is a cost-effective strategy, was lower than the 5-6% previously reported in non-dutch publications. Implications of the study The implications of the study are those associated with the authors' conclusions, as recorded above, within the caveats described above. Source of funding None stated. Bibliographic details Postma M J, Bakker A, Welte R, van Bergen J E, van den Hoek J A, de Jong-van den Berg L T, Jager J C. Screening op asymptomatische infectie met Chlamydia trachomatis in de zwangerschap: gunstige kosteneffectiviteit bij een prevalentie van tenminste 3%. [Screening for asymptomatic Chlamydia trachomatis infection in pregnancy: costeffectiveness favorable at a minimum prevalence rate of 3% or more] Nederlands Tijdschrift voor Geneeskunde 2000; 144(49): PubMedID Other publications of related interest Postma M J, Welte R, van den Hoek J A R, van Doornum G J J, Coutinho R A, Jager J C. Opportunistische screening op genitale infecties met Chlamydia trachomatis onder de seksueel actieve bevolking in Amsterdam. II Kosteneffectiviteitsanalyse van screening bij vrouwen. Nederlands Tijdschrift voor Geneeskunde 1999;143: Indexing Status Subject indexing assigned by NLM MeSH Adolescent; Adult; Chlamydia Infections /economics /epidemiology /prevention & control /urine; Chlamydia trachomatis /isolation & purification; Cost-Benefit Analysis; Female; Humans; Mass Screening /economics; Netherlands /epidemiology; Pregnancy; Pregnancy Complications, Infectious /economics /epidemiology /microbiology /prevention & control /urine; Prenatal Care /economics AccessionNumber Date bibliographic record published 31/01/2002 Date abstract record published 31/01/2002 Page: 6 / 6